What (non-electronic) instrument or sound making device makes the closest to a pure single frequency sine wave? I am under the impression that things like string instruments have all sorts of overtones, or, er… stuff.
I was whistling the other day and it came to my mind that a good clean whistler can make a nice tone. However, I am not an expert at these sorts of things.
So, what is it? Is a simple whistle (human lips) pretty close to a sine wave? Is something else better?
What do you mean by electronic? A Hammond organ produces very near a sine wave once all the effects are off.
It uses electricity, but it’s very much mostly a mechanical instrument. Like a pipe organ having a bellows, I am positive you could get someone to hand-turn the tonewheels and reproduce the sound by using something similar to a mechanical wind up phonograph.
A flute would be deficient in overtones; a trumpet would have a surplus. I can’t think of any acoustic instrument that produces only the primary pitch without some harmonics. The harmonics are what gives an instrument its “color.”
Not quite. The tone wheels create sound by electro-magnetic means, not mechanical. Hand-turning, without electricity, there is no sound at all other than the grinding of ancient bearings.
Whistling produces a fairly pure tone. Woodwind instruments are also commonly cited as being the closest instruments to pure sine waves.
This site lets you download a pure sound wave, and as you say no acoustic instrument sounds anything like that. I’m not sure it’s physically possible.
Only partly. The initial chaotic sound when the note is first sounded or struck also gives an instrument much of it’s character.
Woodwinds? I can believe flutes, but the others are rich in overtones. Think of the raspy sound from a clarinet or saxophone - that raspiness is the sound of harmonics. That’s not even mentioning the oboe and bassoon
A tuning fork
Tuning fork is actually a pretty good candidate. The initial strike is full of noise, but after you wait a couple seconds the tone becomes very pure. It’s still not a perfect sine wave but it’s probably closer than you’ll get with any musical instrument.
as mentioned a stabilized tuning fork is best, they are used as a frequency source.
other tuning aids like a chime bar or pitch pipe would make cleaner tones.
How about a singing wine glass (crystal glass with your finger rotating around the top) – that always seemed like a very pure tone to me.
Ah, I forgot about the ol’ tuning fork. That is kinda their job.
I know I have read that the ocarina is the only regular musical instrument to produce a pure sine-wave tone. According to Wikipedia:
As most ocarinas produce quite high notes anyway, these overtones may well be beyond the range of human hearing.
See also the last paragraph here.
A Captain Crunch whistle can make a pretty pure 2600Hz tone.
I once put a microphone into an oscilloscope and whistled. It made what appeared to be a perfect sine wave. I could vary the frequency quite easily and cleanly.
I don’t doubt that there were overtones (multiples of the fundamental frequency) – there are in everything.
A bar, simply supported on each end, will produce a very pure fundamental tone that is a sine wave, but there are inevitably higher order harmonics. This is what you hear with an instrument like a xylophone, glockenspiel, or marimba. It’s a very pure tone, and seems to cut through any other sound.
string instruments also produce fundamental tiomes with higher harmonics – harps, lyres, guitars, and pianos, and all their relatives.
You also get good fundamentals from wind instruments – flutes, fifes, coke bottles you blow across the top of, organ pipes. (Reed instruments are more complex)
Orchestras take their onstage pitch by the oboe. Of course it’s not a pure sine wave – it is clearly an oboe, after all – but its purity of tone and its loudness (and, I suspect, the extraordinary sensitivity of how local conditions effect pitch with reeds) sets the tone. Finally the concertmaster matches it and the rest of the herd tune up.
Here’s some additional information on the acoustic properties of the ocarina (warning: Comic Sans) :
One of my fellow physics teachers had a student who was one of the best vocalists in the state. He had her sing into a microphone a given pitch (she had perfect pitch and could hit any note within her range on request). He used it as a demonstration, and said the sine wave she could create was perfect.
Singing in a tile shower stall --or better yet, a metal enclosure – will increase purity enormously.
Bingo. We have a winner. 
Why does the tuning fork work so well? (Real question.)
Because it’s just closely ping-ponged air?